Like the Ferro graph tape deck the smaller tandbergs and a whole bunch of Ampex 1000 and 2000 models, they all had serious mechanical compromises. The chassis of the A-77 was very delicate, the switches and volume controls were very fragile. The machine performed well in the beginning, but with a lot of hours began to fail in so many ways. The B-77 and the A700 were better machines, but still light weights.
Marantz units are worth their weight in gold in some markets, but the 8B didn't come close to the MC240. The model 9 was a true performer,but a pair of MC-75's out performed them. The Macs didn't have the cool factor at the time. Though the C-22 electronically wiped the 7C, the touch and feel of the controls sold a lot of units for Marantz. The 10b was a pioneering great unit. But a MR 78 with MPI-4 wiped the 10b in metropolitan areas where weak stations were next to very powerful ones and the 10B couldn't select between the two. In rural areas with stations on adjacent channels the 78 again out performed the 10b. I know the Macs again weren't as cool as a 10B, and therefore will never rate as high in most folks minds. And I hate to have to say this, but all the other tube stuff didn't qualify even for third fiddle. That includes Dyna, Citation, Fisher, Scott, Grommes, Sherwood, Eico, etc etc etc. Even Altec tube amps, were big compromises. So if you want vintage, and want the best of the best. Keep your eyes open for good Marantz and Mac pieces ands have them restored. They may last another 50 to 60 years. Of course if you have the coin their is a new version of the C-22 MKIII with a MC input and MC75's and 275's. If you need big power. Theres the MC2301 and Audio Classics has the best tube amp ever made in the 20th Century, the MC3500 for sale totally reconditioned.